/**
 * Licensed to Apereo under one or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information regarding copyright ownership. Apereo
 * licenses this file to you under the Apache License, Version 2.0 (the "License"); you may not use
 * this file except in compliance with the License. You may obtain a copy of the License at the
 * following location:
 *
 * <p>http://www.apache.org/licenses/LICENSE-2.0
 *
 * <p>Unless required by applicable law or agreed to in writing, software distributed under the
 * License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
 * express or implied. See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apereo.portal.portlet;

import javax.portlet.PortletRequest;
import org.springframework.expression.EvaluationException;
import org.springframework.expression.Expression;
import org.springframework.expression.ParseException;

/**
 * IPortletSpELService provides an interface for parsing strings using the Spring expression
 * language. Strings are assumed to be a potential mixture of SpEL expressions contained inside a ${
 * } and text string content. For example, a portal-relative URL path might be formatted as
 * ${request.contextPath}/my/path.
 *
 * <p>Possible spring attribute values are:
 *
 * <ul>
 *   <li>request - portlet Request
 *   <li>userInfo - map of User Info available to the portlet
 *   <li>@beanName - bean in spring context
 * </ul>
 *
 * @since 4.2
 */
public interface IPortletSpELService {

    /**
     * Parse the supplied string by replacing any ${ } blocks with the SpEL-evaluated value.
     *
     * @param expressionString string to be evaluated
     * @param request portlet request
     * @return evaluated string
     */
    String parseString(String expressionString, PortletRequest request) throws EvaluationException;

    /**
     * Parse the supplied string by replacing any ${ } blocks with the SpEL-evaluated value,
     * returning the desired type if possible.
     *
     * @param expressionString string to be evaluated
     * @param request portlet request
     * @return evaluated object
     * @exception EvaluationException
     */
    <T> T getValue(String expressionString, PortletRequest request, Class<T> desiredResultType)
            throws EvaluationException;

    /**
     * Returns a SpEL Expression using the standard Parsing Context (uses ${ }). Allows you to
     * supply your own {@link org.springframework.expression.spel.support.StandardEvaluationContext}
     * to evaluate the expression against any objects you want. Refer to SpEL API or review the code
     * in {@link org.apereo.portal.portlet.PortletSpELServiceImpl}.
     *
     * @param expressionString string to be evaluated
     * @return SpEL Expression
     * @throws ParseException Error in expression string format
     */
    Expression parseExpression(String expressionString) throws ParseException;
}
